Boraria stricta ( Brölemann, 1896 )

Shelley, Rowland M., McAllister, Chris T., Nagy, Christopher M., Weckel, Mark E., Christie, Roderick G., Wilson, Paul & Wilson, Allan, 2011, Distribution of the American milliped genus Boraria Chamberlin, 1943: Introductions of B. stricta (Brölemann, 1896) in New York and B infesta (Chamberlin, 1918) in Connecticut; indigenous occurrence of B profuga (Causey, 1955) in Louisiana (Diplopoda: Polydesmida: Xystodesmidae)., Insecta Mundi 2011 (194), pp. 1-8 : 2-4

Boraria stricta ( Brölemann, 1896) ( Fig. 1-2 , 5)

Distribution. Boraria stricta , the only representative in South Carolina and Georgia, occupies a large, continuous area with one and perhaps two proximate allopatric populations and a distant introduced one. The continuous area extends, north/south, from northern Floyd Co., Virginia, to northern Lumpkin Co., Georgia; east-west, it ranges from the western Piedmont Plateau of North Carolina (Wilkes, Burke, and Rutherford counties) and the westcentral Piedmont of South Carolina (Union and Spartanburg counties) to the western periphery of the Blue Ridge Province in Virginia and Tennessee (Fig. 13). The milliped has not been encountered in Tennessee south of the GSMNP, so the area encloses the indigenous occurrences of both B. infesta and B. deturkiana except for the Monroe Co., Tennessee, locality of the former. In addition to the allopatric population in the Kings/Crowders Mountains Inselberg, the Bland Co. locality, around 48 km (30 mi) west of the main area, may represent such in Virginia. This record establishes the genus and species in the Ridge and Valley Physiographic Province and suggests occur- rence in the Appalachian Plateaus Province (Allegheny Mountains) in southern West Virginia, only 9.6 km (6 mi) to the northwest (Fig. 12-13).

The New York population, some 704 km (440 mi) to the north-northeast (Fig. 12), constitutes the first record of B. stricta outside the general southern Appalachian region. In the 115 years since its description ( Brölemann 1896), copious samplings in suitable environments to the north in Virginia, Maryland, Pennsylvania, and New York have not yielded a single individual of B. stricta , so its occurrence in Mianus River Gorge Preserve (MRGP) can only be interpreted as a rare, intra-continental, human aided introduction that has established a reproducing population.

Published records. Virginia: Floyd, Franklin, Grayson, and Patrick counties ( Chamberlin and Hoffman 1958; Hoffman 1965, 1999). Tennessee: Blount, Greene, Johnson, and Sevier counties ( Chamberlin and Hoffman 1958, Hoffman 1965). North Carolina : Alexander, Ashe, Avery, Buncombe, Burke, Caldwell, Clay, Cleveland, Gaston, Graham, Haywood, Henderson, Jackson, Macon, Madison, Mitchell, Rutherford, Swain, Transylvania, Watauga, Wilkes, and Yancey counties ( Chamberlin and Hoffman 1958; Hoffman 1965, 1999; Filka and Shelley 1980, Shelley 2000). South Carolina : Oconee and York counties ( Hoffman 1965, Filka and Shelley 1980). Georgia: Dawson and Rabun counties ( Chamberlin and Hoffman 1958; Hoffman 1965, 1999).

New records. Virginia: Bland Co., 2.4 km (1.5 mi S Suiter, M, 26 April 1980, D.W. Ogle (VMNH). Floyd Co., Twin Falls, 2.6 km (1.6 mi) W Copper Hill, M, 2 July 1974, D. Surface (VMNH).

Tennessee: Cocke Co., Great Smoky Mountains National Park (GSMNP), Cosby Picnic Area, M, 19 June 1976, R.M. Shelley (NCSM). Sevier Co., GSMNP, Roaring Fork Motor Nature Loop near Gatlinburg, M, 19 June 1976, R.M. Shelley (NCSM).

South Carolina : Spartanburg Co., Croft State Park, M, 20 August 1976, R.M. Shelley (NCSM). Union Co., 10.2 km (6.4 mi) NW Union, F, 2 May 1977, R.M. Shelley (NCSM).

Georgia: Dawson Co., Amicalola Falls State Park , 2M, 16 April 1978, R. M. Shelley, R. E. Ashton ( NCSM). Habersham Co. , Tallulah Falls, M, April 1891, L.M. Underwood ( USNM) ; and Cornelia, M, 11 July 1978, R. M. Shelley, W.B. Jones ( NCSM). Lumpkin Co., 15.4 km (9.6 mi) NE Dahlonega, 3M, 3 juvs., 16 April 1978, R. M. Shelley, R. E. Ashton ( NCSM) .

New York: Westchester Co., Bedford, MRGP (41 o 11’ 11.5”N, 73 o 37’ 15.4”W), 10M, 9F, 2 juvs., 30 April 2010, C. Nagy (NCSM, FSCA). Introduced Population, New State Record.

Remarks. The apically subhastate gonopods (Fig. 5), coupled with the bimaculate, yellow/black color pattern and the relatively narrow body proportions ( Fig. 1-2 ) distinguish B. stricta from congeneric species and sympatric xystodesmids. It inhabits deciduous leaf litter and typical xystodesmid environments ( Shelley 1981, Shelley and Whitehead 1986) but is unique in tolerating saturated, muddy/mucky biotopes ( Fig. 3 ) even with small amounts of standing water. Hoffman (1965) characterized B. stricta as “more nearly semiaquatic than any other milliped I know,” and a likely spot to encounter it is on or beside a trail at a stream/creek crossing ( Hoffman 1950, personal observations of RMS).

Mianus River Gorge Preserve (http://www.mianus.org/) is located approximately 1.6 km (1.0 mi) south of Bedford, New York, 41.6 km (26 mi) northeast of the Bronx, and 24 km (15 mi) north-northwest of Stamford, Connecticut. In 2000, a xystodesmid with the color pattern and body proportions of B. stricta was first observed in the damp, cool gorge habitat, which consists primarily of post-agricultural oakhickory woodlands and old-growth eastern hemlock stands, and hence is similar to the milliped’s native Appalachian environments. Based on known distributions, the only xystodesmids expected in southern New York are Apheloria virginiensis corrugata (Wood, 1864) , Sigmoria (Rudiloria) trimaculata trimaculata (Wood, 1864) , and Pleuroloma flavipes Rafinesque, 1820 ( Bailey 1928; Blake 1931; Jacot 1938; Chamberlin 1940; Eaton 1943; Hoffman 1949, 1951, 1957, 1999; Shelley 1980; Kevan 1983; Shelley and Whitehead 1986), but the photo posted on the Bugguide website (http://bugguide.net/node/view/37) quickly eliminated the first two. With variable size and body proportions ( Shelley 1980), P. flavipes was a possibility, so in summer 2009, CMN sent the Gorge sample to RMS, who recognized B. stricta , which constitutes its first record outside the southern Appalachian region, some 704 km (440 mi) to the south-southwest. Residential yards in the Gorge neighborhood are extensively landscaped with ornamental gardens and nursery plants, the probable source of the original introduction. The Preserve was systematically surveyed for B. stricta in 2008-09 using the mustard solution method of Hale (2007); density estimates of 4.1 + 13.9 individuals/m 2 (mean+ SD) throughout the area and 1.74 + 2.93 individuals/m 2 at streamside plots (via visual and cover searches) indicate rapid population growth after introduction, which was at least 11 years ago based on the aforementioned first sighting in MRGP. Searches at nearby preserves in Westchester Co. (Ward Pound Ridge, Westmoreland Sanctuary, Greenburgh Nature Center, Teatown Lake Reservation, and Cranberry Lake) and Greenwich Audubon, Fairfield Co., Connecticut, have not yielded B. stricta . It is commonly found in moist conditions under logs and in streambeds in MRGP but also inhabits nonriparian hardwood uplands and old-growth eastern hemlock stands that are comparatively dry and virtually devoid of deciduous vegetation. Staff and student researchers at the Preserve are investigating the ecological impact of B. stricta on native species; monitoring this population and determining its extent in Westchester Co. constitute worthy projects for regional nature clubs and high school biology classes. Population ecology studies would also be productive.

Figures

Figures 1-4. Boraria spp. 1) A cluster of B. stricta under leaves on saturated substrate at Mianus River Gorge Preserve, Westchester Co., New York. 2) An individual of B. stricta climbing a log at this site; note the juvenile in the depression left of center. 3) A tributary of the Mianus River in the Preserve showing leaf litter and the surrounding deciduous forest, an ideal environment for B. stricta. 4) B. infesta from Avon, Hartford Co., Connecticut.